The effects of thiothixene (P-4657 B) in 34 psychotic children and adolescents were studied; 29 were schizophrenic subjects, 17 had been ill for less than one year and 12 for a longer time. Good results were observed in 20 cases, with evident improvement of the psychiatric symptomatology. Tolerance has been very good and side effects minimum. Subsidiary examinations (hemoglobin level and leucocyte count, tests for evaluation of the functional state of the liver and electroencephalogram) were normal. The thiothixene was observed to have an antipsychotic effect when used as the first treatment, as well as when the patient had already been treated with other antipsychotic drugs without satisfactory result. Remarkable effects were noticed on apragmatism and emotional blunting. Sedative effect was observed on crises of psychomotor instability. Positive result, were almost always noticed with minimum dosage (5 — 10 mg per day) in the early stage of treatment.